1. Technical Field
The present invention relates to a method for making hose assemblies of the type particularly well adapted for carrying vehicle fuels. More specifically, the subject invention relates to a method for constructing a hose assembly having an inner fluorocarbon polymer liner and a braided layer thereabout.
2. Description of the Related Art
Hose assemblies used for carrying vehicle fuels are well known in the art. Such hose assemblies should preferably be strong and resistant to both heat and chemical degradation. The hoses are subject to chemical breakdown due to exposure to various fuels and additives in the fuels which flow through the interior of the hose. Further, these hoses are typically routed through the engine compartments of vehicles to deliver fuel to the engines. These engines are hot and, thus, the hoses used to carry the fuels are subjected to thermal breakdown from the heat.
TEFLON hoses provide the necessary physical characteristics for carrying fuels. A major drawback with these types of hoses, however, is that when used alone, they tend to become bent during installation resulting in a kink. This kink or deformation remains permanent and provides constant resistance to fluid flow through the hose. To solve this problem, hose assemblies have been constructed which include an inner TEFLON tubular member surrounded by tightly wound metallic braid. The metallic braid allows the TEFLON inner tubular member to bend to a certain degree without kinking. However, if bent passed a certain point, the metallic braid aids in the kinking of the inner tubular member. This type of assembly has three major disadvantages. First, the metallic braid tends to abrade the exterior of the inner tubular member. This causes leaks from the inner tubular member. The second problem is that the exterior metallic braid casing is thermally and electrically conductive. More important is that the metallic braid will retain the heat and transfer the heat to the fuels moving through the inner tubular member causing fuel system problems. Finally, when used in an automotive environment, the metallic braid transmits noise during operation of the vehicle which is undesirable.
To avoid these problems associated with metallic braided layers, the inner tubular member may be supported with an non-metallic braided material. Although the substitution of non-metallic braided material avoids many problems associated with metallic braiding, several problems exist. First, hose kinking remains a problem due to relative longitudinal movement between the inner tubular member and the braided layer. That is, due to relative slippage between inner tubular member and the braided member, the hose assembly is susceptible to kinking. Second, the hose assembly is usually exposed to external heat and chemicals and thus must be resistant to heat and chemical degradation. Most non-metallic braiding material do not provide the requisite heat or chemical resistance required. Third, hose assemblies generally encounter rough surfaces after installation; that is, they rub against engine components. Accordingly, due to exposure to frictional movement, the hose assembly must be resistant to abrasion.
Co-pending application U.S. Ser. No. 657,084 filed Feb. 19, 1991 now U.S. Pat. No. 5,142,782 and its co-pending divisional application U.S. Ser. No. 416,151 filed Oct. 2, 1989 now abandoned which is a continuation-in-part of U.S. Ser. No. 305,641 filed Feb. 2, 1989 and now abandoned, which are all assigned to the assignee of the subject invention, disclose a method for making a coated braided hose assembly. The method comprises the steps of extruding an inner tubular member liner of a polymeric fluorocarbon material and subsequently disposing glass fibers about the exterior of the liner. The inner tubular liner and the braided layer are then passed through a reservoir containing an aqueous dispersion of a fluorocarbon polymer. The fluid of the dispersion, water, is later removed from the hose assembly leaving a fluorocarbon polymer coating dispersed throughout the braided layer.
U.S. Pat. No. 4,311,547 to Biggs et al. issued Jan. 19, 1991 discloses a hose assembly including an inner rubber liner having a reinforced layer braided thereabout. A solidifiable liquid polymer is embedded into the interstices of the reinforcement layer so as to bond the inner rubber liner to the reinforcement layer braided thereabout. The solidifiable liquid polymer may comprise plastisol, aldehyde, epoxy or isocyanate resins. A cover layer may be disposed about the reinforcement layer and bonded thereto by the solidifiable liquid polymer. The cover layer may comprise the same material as that which unites the reinforcement layer and the inner liner, that is, in addition to bonding the inner rubber liner to the reinforcement layer, the solidifiable liquid polymer may also act as the cover layer. Although the solidifiable liquid polymer does in fact bond the inner liner to the reinforcement layer disposed thereabout, it does not sufficiently resist abrasion, heat, or chemical degradation.
The U.S. Pat. No. 4,215,384 to Elson issued Jul. 29, 1980 discloses a hose construction and method for making the same. The hose assembly includes an inner organic polymeric liner having a braided material disposed thereabout. The assembly further includes an outer coating of an organic polymeric material. A conductive strip is disposed within the inner tubular liner for conducting electrical charges throughout the interior of the liner. The assembly further includes end fittings on each end of the inner liner for allowing fluid to be conducted therethrough.
U.S. Pat. No. 4,007,070 to Busdiecker issued Feb. 8, 1977 discloses a hose assembly having an inner organic polymeric liner. The liner has a braided layer disposed thereover. An outer protective layer constructed from an organic polymeric material is disposed about the exterior of the braided layer. The Busdiecker patent discloses the use of an adhesive to bond the inner liner to the braided material. The adhesive also coats the braided material for securing the braided material to an outer protective layer.
The U.S. Pat. No. 4,394,705 to Blachman issued Jul. 19, 1983 discloses a hose assembly including an inner fluorocarbon liner including a reinforcing braided layer disposed thereabout. A cover layer having chemical and abrasion resistant properties is disposed about the braided layer protecting the inner liner and braided layer.